Dressed and softened regenerated cellulose products



Patented Mar. 2, 1943 mmsss @I- sous!) arcsnsm'rrp csmuaosn rao nc'rs No Drawing. Application March 7, 1939, Serial No. 260,436. In Gy January 31, 1934 Claims. (Cl. 117-144) is in part disclosed in application Serial No. L327, filed January 31, 1935, now Patent No. 3,273,636.

This invention relates to regenerated cellulose and softening agents therefor. Regenerated celulose products and particularly those obtained from aqueous cellulose solutions are commonly seated with glycerol to impregnate the same for ;he purposes of preventing shrinkage or for the )UIPOSE of softening the material. When imiregnating the regenerated cellulose in order to Jrevent drying out and shrinking, concentrated glycerol solutions are generally employed wherel8 for merely softening the same dilute solutions we preferable.

However glycerol is very hygroscopic and for his reason has several disadvantages. When lsed as a softening agent the glycerol renders he cellulose products extremely sensitive to moisture so that even a slight increase in the.

lumidity of the air is suficient to cause a too treat and disadvantageous softening of the maerials and even'to cause them to swell, so that ellulose foils lose their shape and their clearless and transparency is materially decreased. time the cellulose products treated with glycerol -ften contain 9 to 12% of glycerol, they are inlined to putrefaction and decomposition. For xample, in an atmosphere of high humidity such ,s found in the tropics the glycerol impregnated ellulose will absorb so much moisture that the materials will readily spoil. The impregnated ellulose products also adhere to each other to n extent to cause considerable loss. Glycerol is fiective as an impregnation agent to prevent hrinkage of the cellulose products but it has erious limitations because of the disadvantages bove discussed.

It has been discovered in accordance with the resent invention that the above noted difficulles can be very much reduced or entirely elimiated by the use of compounds of glycerol in rhich a suflicient proportion ofthe hydroxyl roups oi the glycerol are eliminated to reduce he hygroscopicity. Furthermore, similar comounds of other similar polyhydric alcohols are lsoeifective as substitutes for glycerol.

The hydroxyl groups can satisfactorily be elim- :ated by reacting the glycerol with aliphatic cids and alcohols for form esters or ethers hereof.

The reduction of the hygroscopicity is in genral greater as the proportion of the hydroxyl roups is reduced. It is also greater as the iolecular weight of the compounds formed is reater, that is to say when the acids and alco- The subject matter of the present application hols substituted for the hydroxyl groups are of higher molecular weight. This replacement of hydroxyl groups can be carried to the extent of producing complete msolubility in water.

It has also been discovered that the glycerol ethers and esters which have a certain water solubility or which can be rendered water soiuble by the addition of low molecular alcohol such as methyl, ethyl or propyl alcohol have a particularly desirable dressing and soi'temng effeet.

It is one of the advantages of the invention that the hygroscopicity can be reduced to such extent as is considered most desirable for an impregnating or softening agent that is to be used under any given conditions. By asuitable combination or mixture ofthe impregnating materials mentioned in an aqueous, alcoholic or alcoholic aqueous solution it is possible to obtain dressing or impregnating agents for treating regenerated cellulose products which will give desired properties thereto. By treatment with such suitably selected mixtures the disadvantages heretofore existing in regenerated cellulose products dressed with glycerol are substantially or entirely eliminated.

It is contemplated that not only glycerol but other polyhydric alcohols of the same type having about 3 to 5 carbon atoms in the molecule and polyglycerols and also alkylene glycols and the like may be used to form the compounds in accordance with the invention for the uses in= dicated although the glycerol is preferred as the base material.

The alcohols which are to be reacted with the glycerol or its equivalent are the normal primary aliphatic alcohols having from 1 to 18 carbon atoms in the molecule. The mono-hydric alcohols are preferred. Those having from 1 to 8 carbon ,atoms are generally preferred. Those having 12 to 18 carbon atoms are preferable when low solubility is desired.

Acids suitable for use for esterificationare the normal primary monocarboxylic aliphatic acids having 1 to 18 carbon atoms and preferably those having from 1 to 8 carbon atoms in the molecule. The munber of hydroxyl groups of the glycerol or its equivalent which are substituted by reaction with the acid or alcohol will depend upon the results desired as above indicated.

The dicarboxylic acids having 1 to 18 carbon atoms in the molecule e. g. oxalic acid, succinic acid, sebasic acid, cyclohexane diacetlc acid, phthaiic acids and the like are also suitable for use in forming esters whereby the hydroml group is substituted.

Aromatic or cyclo aliphatic compounds of alcoholic character may also be used in the formation of suitable ethers, such for example as glycerol monoor diphenyl ether and glycerol monoor di-cyclo hexyl ether.

Among the numerous suitable compounds prepared from glycerol or its equivalents may be cited Ethyleneglycoi-monomethylether Ethyleneglycol-monobutylether Ethyleneglycol-monododecylether Ethyleneglycol-dimethylether Glycerol-monomethylether Glycerol-monoethylether Glycerol-monobutylether Glycerol-monooctylether Glycerol-monocetylether Glycerol-dimethylether Glycerol-dipropylether Glycerol-dioctylether Glycerol-didodecylether Glycerol-diphenylether Glycerol-dicyclohexylether Glycerol-trlnaphtenylether Polyglycerol-monododecylether Polyglycerol-monooctadecenylether Penta erythrite-monooctylether Penta erythrite-dibutylether Ethylene glycol-monoacetate Ethylene glycol-monocaprylate Glycerol-monopropionate Glyc'erol-monolaurate Glycerol-dibutyrate Glycerol-oxalate Glycerol-adipinate Glycerol-phthalate Example 1 To make soft and elastic cellulose-foils out of cellulose-xanthogenate one passes the ready formed film in a humid of half-dried state through a warm watery impregnation-bath of about 35 and containing 1.5% of triacetinebesides 1.5% of glycerol-monomethylether. The film is then dried in the usual way and cut to the desired size. The thus obtained foils show an excellent flexibility and also during a long storage they remain smooth, clear and transparent. Those foils are able to offer certain resistance to the reaction of aqueous vapour. Instead of the said impregnation-agent it is also allowed to employ merely a 3% solution of glycerolmonomethylether or glycerol-monoethylether or a mixture of 2% glycerol-monomethylether and 1% glycerol-monooctylether.

Example 2 Humid or half-dried cellulose-products obtained according to the cupric oxide-ammoniaasravos cellulose-procedure are treated, e. g. in the form of ribbons, with an alcoholic-watery solution (about 20 to 25% of ethylalcohol) containing 4% of glycerol-dimethylether and 2% of glycerol-monomethylether. The cellulose products are then subject to the further treatment and after the drying they are of an excellent elasticity and softness. Instead of the above impregnation-bath one may employ with a similar good success an alcoholic-watery solution of 3% of glycerol-monoethylether and 2% of polyglycerol-dodecylether.

Example 3 Artificial guts or tubes, made of cellulose according to the wellknown method, are impregnated in an aqueous bath containing 1.5% of glycerol-mononaphthenylether, 2% of glycolmonomethylether and 0.8% of triacetine. The products impregnated with this liquid are of a good elasticity and also during a long storage they do not incline neither toshrinkage nor to sticking together. Instead of the above indicated impregnation-bath-admixture one may likewise use a mixture of 4 parts of glycerolmonomethylether and 1 part of isopropylalcohol 'or a mixture of 3 parts of polyglyceroldodecylether, 2 parts of-glycerol-monoethylether and 1 part of isopropylalcohol.

The various products may be produced in accordance with known methods of the formation of ethers and esters. For example, by allowing to react the glycerol or the other polyvalent alcohols in the form of their mineral acid monoor polyesters with alkalimetal compounds of the aliphatic or cycloaliphatic alcohol series or by esterification of the glycerol or of the other polyvalent alcohols with monoor dibasic carboxylic acids or their functional derivatives.

The foregoing particular description is illustrative merely and is not intended as defining the limits of the invention. It will be understood that equivalent treating agents can be formed by using different starting materials than those specifically mentioned.

We claim:

1. A dressing and softening agent for regenerated cellulose products consisting of an aqueous impregnation liquid containing 1.5% of glycerolmonoethylether and 1.5% of triacetin.

2. A dressing and softening agent for regenerated cellulose products consisting of an aqueous impregnation liquid containing a water soluble ether of glycerol with an aliphatic alcohol having t1 to 8 carbon atoms in the molecule and triaceine.

3. A regenerated cellulose composition containing as a dressing and softening agent an aqueous impregnation liquid containing 2% of glycerol monomethyl ether and 1% of glycerol monooctyi ether.

4. A regenerated cellulose composition containing as a dressing and softening agent an aqueous impregnation liquid containing a watersoluble ether of glycerol with an aliphatic alcohol having one to eight carbon atoms in the molecule.

5. A regenerated cellulose composition containing as a dressing and softening agent an aqueous impregnation liquid containing a watersoluble ether of glycerol with an aliphatic alcohol having one to eighteen carbon atoms in the molecule.

WALTER GELLENDIEN. JOHANN EGGERT. 

